Man who murdered girlfriend at Plymouth hotel sentenced to nearly 20 years in prison

On Monday, a Minneapolis man learned his future after being convicted of killing his girlfriend in a Plymouth hotel last summer.

Alex Garfield Keaton, 39, of Minneapolis, was sentenced in Hennepin County court to 19 years (228 months) at the St. Cloud Correctional Facility, with 283 days of credit for time served.

Keaton entered a guilty plea to one count of second-degree murder without intent on April 3.

Hennepin County court documents show the state sought an aggravated sentence in Keaton’s case due to the particular cruelty of the crime and the fact that it was committed in the victim’s “zone of privacy.” The typical sentencing guidelines for this crime called for 128-180 months in prison.

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Police were called to the Red Roof Inn in Plymouth on Feb. 7, 2022, for a report of someone not breathing. There, officers found 41-year-old Lisa Petersen, of Buffalo, unconscious and pale. Aid was provided but she was pronounced dead at the scene.

While providing CPR, officers noted Petersen had bruises all over her body, including both arms, chest, sides, legs, face and neck.

Keaton told police that Petersen had decided to sleep on the floor. At one point, he heard a thud, saw Petersen gasping for air, and believed she’d dropped a 10-pound weight on herself, the complaint states.

Surveillance video showed Petersen, Keaton and three children arriving at their room shortly before 10:30 p.m. The children went to the vehicle quickly at around 11 p.m. but returned, and no other action was seen until Keaton tried carrying Petersen’s limp body to a stairwell at around 2:20 a.m. However, he returned to the room, saying he started CPR while his daughter called 911.

However, the medical examiner found severe trauma to Petersen’s body that happened shortly before she died. With Keaton and the three kids the only other people in Petersen’s room, investigators believe Keaton was the only person able to inflict such injuries on Petersen.

Detectives also found Keaton had searched online for Minnesota’s sentencing guidelines, attorneys and murder for hire a couple of weeks after Petersen’s death.